Machine-switching telephone-exchange system



L. POLINKOWSKY.

MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM.

. APPLICATION FILED IULY 16,1918- I 1,339,575. Patented May 11,1920,

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Specification of Letters Patent.

Patented May 11', 1920.

Application filed July 16, 1am. sen-a1 n01 245,223.

To all whom it may concern:

Be it known that I, LIrA POLINKOWSKY, a citizenof Russia, residing at 70 WVestbourne Terrace, Hyde Park, London, W., England, have invented certain new and useful Improvements in Machine- Switching TelephoneExchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to machine switching telephone: systems and more particularly to systems in which an exchange network is made up of two or more central su' itching' points, the connecting lines between such central points being preferably of the tw'o wire type;

A particular feature of the invention resides in the arrangement of circuits and apparatus in such a manner that, upon the release of a two=wire connecting circuit between switchingpoints on one of such switching points, the premature seizure of such connecting circuit or trunk line at the switching point at which it was released will not result in interference with existing established connections, in the holding out of service of switching apparatus or in the a'l'aortive extension of the call subsequently extended to such connecting circuit or trunk line. i

The accompanying figure of the drawing shows diagrammatically atrunk lineof the character referred to and the switching apparatus associated therewith, together with sufficient circuits and apparatus of a well known type of machine switching system, to indicate clearly the character and embodiment of the invention disclosed.

The form of the invention shown in the drawing will be best understood from a description of the operation thereof. The apparatus on the left of the drawing is presumed to be located in one exchange and the apparatus on the right of the drawing is in another exchange, the two-wire trunk line extending between such exchanges. Of the apparatus indicated in the exchange in which the call originates, that is, to the left of the drawing, only so muchis shown as is'required to make clear the characteristics of the present invention. This exchange may he of any preferred type, either full automatic or semiautomatic, such, for example, as the automaticexchange disclosed in British Patent No. 5653 of 1913'.

The system in which the present invention is assumed: tobeembodied, however, is a system: in which the extension of a call in volves the use of a first group selector, as indicated at the originating exchange, a second group selector at the, distant exchange,- as well as the finalselectoratsuch distant exchange, and, if desired, additional group selectors at either of such exchangesi It will be understood that the apparatus associated with the first group selector at the originating exchange operates briefly as follows: The call having been extended to such exchange has been connected to a connecting circuit thereat indicated at 99, and also to an idle registering and controlling equipment, indicated at 98.

The numerical designation of the desired line having been registered upon such equipment, either by the operation of the" subscribersimpulse transmitter, if the exchange is full automatic, or by means of the perators numerical keys, if the exchange is semiautomatic, the usualsequence switch controlling the sequence switch contact 82 indicated at the upper left hand part of the drawing moves into' its third position in which the brush choosing operation of the first group selector takes place in the well known manner, the relay 97 being energized over sequence switch contact 82 and the stepping relay 96 of the controlling equipmentbeing intermittently deenergizedin the well known manner; When the stepping relay 96' has been energized and deenergizedthe proper number of times to accomplish the correct brush selection in the first group" selector, the switch 95 is opened to cause'the cessation of such selection, and, the relay 97 being deenergized, the sequence switch referred to moves into its fifth position. The movement of the brush carriage of the first group selector now takes place in the usual manner due to the energization of the brush carriage power magnet 94 over baclc contact of test relay 92 and sequence switch contact 81. In this movement which is to select an idle line of the group of trunk lines selected under the control of thecontrolling equipment 98"',-the-test relays 93' and 92' coeperate in the usual manner and having found an idle line seize such line and cause the cessation of movement of the brush carriage in the well known manner, also causing the movement of the sequence switch'referred to out of its fifth and into the sixth position. In this position the sequence switch contacts 91 bottom and 90 bottom being closed, the fundamental circuit is extended to the apparatus of the second group selector and when the sequence switch contact 89 closed in the fourth position of the controlling equipment sequence switch, such circuit, provided the sequence switch 10 at the second group selector and its governor spring 11 is in its normal position, will be completed to energize the line relay 31 at said second group selector.

The selection controlling operation in the second group selector now takes place, the sequence switch 10 ismoved into its second position by the energization of the relay 31, and the circuit for the tripping spindle 32 is closed over the sequence switch contact 12 bottom and the front contact and armature of the relay 31. hen the stepping relay 96 at the controlling equipment has been intermittently shunted the requisite number of times by the operation of the interrupter 33 of the tripping spindle 32, the

switch 95 will be opened in the usual manner to terminate the selecting operation of such tripping spindle by causing the deenergization of the relay 31 in the well known manner. Such deenergization causes the movement of the sequence switch 10 into its third position by the closure of a circuit including the sequence switch contact 13 top. In this position the movement of the selector brush carriage takes place in the usual manner, cooperating with the test relays 35 and 36,.adapted to be connected to ground over sequence switch contacts 30 and 20, respectively, to select and seize an idle trunk line in the group of trunk lines determined by the set position of the tripping spindle 32. in this position the sequence switch contacts 14: bottom and 15 bottom are opened and the sequence switch contact 14: top and 15 top are closed. Consequently the fundamental circuit which has, in positions one and two, been connected to ground over the sequence switch contact 14 bottom and to battery through the relay 31 over the sequence switch contact 15 bottom, is now connected to the repeating coil 84:. Should the sequence switch contact 89 and the switch 95 at the controlling equipment he again closed (the sequence switch contact 89 in the sixth position of the controlling equipment sequence switch) before the completion ofthe selection of an idle line leading to a final selector of the desired group, no false energization'of the relay 96 will take place as,.

although the fundamental circuit is complete both at the controlling equipment and at the second group selector through the repeating coil, no battery is provided therein.

The selection of an idle trunk line in the desired group having been completed, the sequence switch 10, responsive to the action of the relay 36, is moved into its sixth position, in which position the fundamental circuit is established metallically through to the final selector chosen, by the closure of the sequence switch contacts 16 top and 17 selector will not be established until such se quence switch contact is closed in such position. On the other hand, if the sequence switch contact 89 and the switch are al ready closed, the fundamental circuit will now be extended to the final selector immediately upon the closure of the sequence switch contacts 16 top and 17 bottom as described.

The two successive selection controlling operations will now take place in the final selector in the well known manner. At the conclusion of these selections, the sequence switch at such final selector will be moved to so increase the resistance in the circuit, connected with the test terminal individual to such final selector that the relay 36 is deenergized and the sequence switch 10 is moved into its eighth position which is the talking position of this sequence switch.

The sequence switch 10 remains in this position until the termination of conversation. Such signals as it is necessary to pass on from the final selector to the connecting cir cuit are repeated around the repeating coil 34 by the supervisory relay 37- and relay 38;

The two windings of the relay 38 are connected in series, the right winding of sufliciently high resistance to prevent the energization of an usual supervisory or other relay to be controlled at the connecting circuit. Relay 37 when energized, however, shunts the high resistance winding of the relay 38, permitting sufiicient current to pass through the circuit to produce the energization of such supervisory or other relay. The relay 38 was energized before the se quence switch 10 came into its eighth posisignals or the movement of the sequence switch. associated with the connecting cit" cuit in any preferred or well known manner.

When it is desired to break down the connection after the sequence switch 10 has come into its eighth position, the usual operations of the apparatus at the connecting circuit, particularly the sequence switch 'thereat, causes the opening of the circuit energizing the relay 38 and such relay closes at its back contact the circuit over the sequence switch contact 28 to drive the sequence switch 10 out of its eighth and into its seventeenth position. In this position the brush carriage is returned to its normal position in the usual manner and the sequence switch is then driven into its first or normal position, the tripping spindle 32 be ing returned in the eighteenth position and the normal position of the sequence switch.

When the sequence switch 10 is in its third position in the establishment of a call, the brush carriage of the second group selector is being moved and the brushes 39, 40 and 41 cooperating with the relays 35 and 36 are hunting for an idle trunk line leading to the final selector. If, at this time, the connection is broken down at the connecting circuit, immediately that the brushes 86, 87 and 88 leave the terminals 83, 84 and 85 individual to the trunk line leading to the second group selectors shown, such trunk line can be immediately seized by some other first group selector which is hunting in the group of trunk lines to which this trunk line belongs. As soon as such seizure has taken place by this first group selector, the fundamental circuit leading thereto will be closed at the controlling equipment and at the sequence switch contacts 91 bottom and 90 bottom, Meanwhile it may be assumed that the second group selector, the tripping spindle of which has been set by the uncompleted extension of the prior call, is still hunting for a final selector and if, under these conditions, when such idle final selector has been found, the circuit is immediately closed thereto, a false connection will be established as, in the event of the subsequent call being extended, the impulse controlling operation which should control the operation of the tripping spindle of the second group selector will be carried over directly to the final selector and cause the improper operation thereof.

In order to prevent this abortive operation of the system, the circuit is so ar ranged that, under all conditions of premature release, even when the sequence switch 10 is in its third position, the breaking down of the prior connection will cause the sequence switch 10 to pass through its complete cycle of operation before a fundamental circuit can be completed again either at or over the apparatus of such second group selector and consequently no abortive connection either of the controlling equip- 'ment of such second group selector or the final selector seized thereby can take place.

The operation of the system shown to produce this result is as follows:

If the premature disconnection takes place in the second position of the sequence switch 10, such sequence switch will move into its third position as though the selection controlling operation had been properly completed and the operation in this event will take place precisely as though a premature disconnection had taken place while the sequence switch 10 was in its third position and the brush carriage was already searching for an idle trunk line.

Assuming, therefore, that the premature disconnection takes place in the third position of the sequence switch 10, immediately that such premature disconnection has caused the sequence switch at the connecting circuit to move out of its sixth position a circuit is established from the battery in the repeating coil 99 over the sequence switch contact 90 top, brush 87, contact 84, sequence switch contact 15 top, the two windings of relay 38 in series, sequence switch contact 14 top, contact 83, brush 86, sequence switch contact 91 top and back to battery. The relay 38 is, therefore, energized.

A circuit is, therefore, closed for the relay 31 including the sequence switch contact 18 and the front contact and armature of the relay 38. The relay 31 energizing closes a circuit over the sequence switch contact 28 bottom to drive the sequence switch 10 out of its third and fourth positions. In the fifth position of the sequence switch 10, the brush carriage is returned to normal provided an idle trunk line has not as yet been found, by the closure of a circuit over the power magnet 42, including the sequence switch contact 19 top and the back contact and armature of the relay 36. Upon the completion of the restoring movement of the brush carriage in the fifth position of the sequence switch 10, in which position, since no circuit is closed to the brushes 39, 40 and 41, no disturbance of the trunk lines over which such brushes pass can take place, the relay 36 is energized over the sequence switch contact .20, interrupter 43 and the home or normal contact thereof, and the se quence switch contact 21.

On the other hand, if, while the sequence switch 10 was moving from its third and through its fourth position, an idle trunk line to a final selector had been found, when the sequence switch 10 came into its fifth position, the relay 36 would have been already energized.

In any event, the relay 36 energized in the fifth position, a circuit is closed over its armature and front contact and the sequence switch contact 13 bottom to drive the sequence switch 10 out of its fifth position. The relay 31 having been maintained energized in the fifth positionof the sequence switch 10 a locking circuit was closed therefor including its armature and front contact and the sequence switch con tact 29, which'locking circuit will be maintained in the sixth position of the sequence switch 10 so that relay 31 is energized in this position although the sequence switch contact 18 is open. Consequently when the sequence switch 10 comes into such sixth position, the sequence switch contact 20 bot tom being open, the circuit which would otherwise be closed for the relay 36 and the relay 35, if an idle trunk line has been seized, is opened and such relay 36 deenergizing the sequence switch 10 is moved im mediately out of its sixth position into its eighth position over a circuit extending from the back contact of relay 36 and the sequence switch contact 19 bottom.

As, by the time the sequence switch 10 comes into its eighth position, the circuit for the relay 38 has been opened at the sequence switch contacts 90 top and 91 top, in the usual course of the premature disconnection initiated from the connecting circuit shown, the relay 38 closes at its back contact a circuit over the sequence switch contact 28 top to drive the sequence switch 10 out of such position and into its seventeenth position. In this position, if the brush carriage is in its normal position, the usual circuit is closed to drive the sequence switch into its first or normal position, whereas if the brush carriage is not in its normal position, it will be restored immediately following such restoration, the sequence switch 10 is moved into its first or normal position in the well known manner.

It will be apparent from this description that no seizure of the trunk line to the second group selector shown over the terminals 83, 84c and 85 by a first group selector utilized for a subsequently initiated call can in any way either hold up the restoration of the second group selector shown to its normal position or the final selector which it may have seized, or by the closure of a circuit to the final. selector cause interference with a call already established over such final selector, or, by the improper extension of a fundamental circuit to an idle final selector seized in connection with the extension of the prior call, from the controlling equipment being utilized in connection with the subsequent call, cause the abortive extension of such subsequent call.

In connection with the third point noted, it will be observed that in the seventh and eighth positions of sequence switch 10 when it might be possible for a subsequent call to be extended to the second group selector shown and the fundamental circuit from the controlling equipment utilized in such subsequent call is closed to the repeating coil 34, no source of current is included in such circuit, and, since the relay 96 is consequently not energized, no detrimental efiect will take place in the controlling equipment or with regard to the extension of the subsequent call. When the sequence switch contacts 14 top and 15 top are open, as the sequence switch 10 leaves its eighth position, no circuit is again closed over the two-wire trunk line extending to the terminals 83 and 84 until the sequence switch being in its first or normal position the second group selector shown is ready to be utilized in connection with the subsequent call and the fundamental circuit from the controlling equipment utilized in such subsequent call being now closed through relay 31, the normal operation of the apparatus of the second group selector will again be. initiated.

What is claimed is;

1. A telephone exchange system comprising a plurality of exchanges, a two-conductor trunk outgoing from one exchange and incoming at a second exchange, means at said one exchange for extending connections to said trunk, a selective switch at said second exchange, circuits appearing at the terminals of said selective switch, means for operating said selective switch to extend said trunk to said circuits, an auxiliary switch having a plurality of controlling positions for said selective switch, means for releasing said selective switch when said auxiL iary switch is in one of its controlling positions, and means for releasing said selective switch in another of the controlling positions of said auxiliary switch when a connection is prematurely released at the outgoing end of said trunk.

2. A telephone exchange system comprising a plurality of exchanges, atwo-conductor trunk outgoing from oneexchange and incoming at a second exchange, means at said one exchange for extending connections to said trunk, a selective switch at said second exchange, circuits appearing at the terminals of said selective switch, means for operating said selective switch to extend said trunk to said circuits, an auxiliary switch having a plurality of controlling positions for said selective switch, means for releasing said selective switch whensaid auxiliary switch is in one of its controlling positions, means for releasing said selective switch in another of the controlling positions of said auxiliary switch, and means for preventing the premature seizure of one tor trunk outgoing from one exchange and incoming at a second exchange, means at said one exchange for extending connections to said trunk, a selective switch at said second exchange, circuits appearing at the terminals of said selective switch, means for operating said selective switch to extend said trunk to said circuits, an auxiliary switch having a plurality of controlling positions for said selective switch, means for releasing said selective switch when said auxiliary switch is in one of its controlling positions, means for releasing said selective switch in another of the controlling positions of said auxiliary switch, and means for preventing the holding out of service of switching apparatus in the event of the premature release of one of said trunks.

4-. A telephone exchange system comprising a plurality of exchanges, a two-conductor trunk outgoing from one exchange and incoming at a second exchange, means at said one exchange for extending connections to said trunk, a selective switch at said second exchange, circuits appearing at the ter minals of said selective switch, means for operating said selective switch to extend said trunk to said circuits, an auxiliary switch having a plurality of controlling positions for said selective switch, means for releasing said selective switch when said auxiliary switch is in one of its controlling positions, means for releasing said selective switch in another of the controlling positions of said auxiliary switch, means for preventing the premature seizure of said trunk, when released, from interfering with existing established connections, and means operating on the premature release of said trunk, for causing a complete cycle of op eration before said auxiliary switch can again control the operation of said selective switch.

5. A telephone exchange system comprising a plurality of exchanges, a two-conductor trunk outgoing from one exchange and incoming at a second exchange, means at said one exchange for extending connections to said trunk, a selective switch at said second exchange, circuits appearing at the terminals of said selective switch, means for operating said selective switch to extend said trunk to said circuits, an auxiliary switch having a plurality of controlling positions for said selective switch, means for releasing said selective switch when said auxiliary switch is in one of its controlling positions, means for releasing said selective switch in another of the controlling posi tions of said auxiliaryswitch, means for preventing the premature seizure of said trunk, when released, from interfering with existing established connections, means operating on the premature release of said trunk for causing a complete cycle of operation before said auxiliary switch can again control the operation of said selective switch, and means for completing'said cycle of operation when it once is started regardless of the subsequent condition of the line that initiated said premature release.

6. A telephone exchange system comprising a plurality of exchanges, a two-conductor trunk outgoing from one exchange and incoming at a second exchange, means at said one exchange for extending connections to said trunk, a selective switch at said second exchange, circuits appearing at the terminals of said selective switch, means for operating said selective switch to extend said trunk to said circuits, an auxiliary switch having a plurality of controlling positions for said selective switch, means for releasing said selective switch when said auxiliary switch is in one of its controlling positions, means for releasing said selective switch in another of the controlling positions of said auxiliary switch, means for preventing the premature seizure of said trunk, when'released, from interfering with existing established connections, means operating on the premature release of said trunk for' causing a complete cycle of operation before said auxiliary switch can again control the operation of said selective switch, and means for rendering said trunk idle upon the initiation of said release and for permitting said trunk to be immediately connected by any calling line before said cycle of operation is completed.

In witness whereof I hereunto subscribe my name this 6th day of May A. D. 1918.

LIPA POLINKOWSKY. 

